平原丘陵过渡区土壤有机质空间变异及其影响因素

研究土壤有机质(SOM)在平原丘陵过渡区域的空间变异规律及其影响因素对指导农业生产实践具有重要意义。选取平原丘陵过渡区域(江汉平原与鄂西山区)作为研究区,采集500个土壤表层(0~20 cm)样本,利用相关分析和逐步回归分析从14个影响因素中选取与土壤有机质密切相关的7个变量作为解释变量:高程、坡度、坡向、有效铁、容重、砾石度、黏粒含量。利用普通克里格(OK),回归克里格(RK)和地理加权回归克里格(GWRK)方法对研究区土壤有机质含量进行预测,并用平均误差(ME)、平均绝对误差(MAE)、均方根误差(RMSE)、相关系数(r)和不精确度(IP)作为验证指标来检验模型的预测精度。结果表明,GWRK插值结果最优,局部空间回归模型可以更好地表明过渡区域SOM的空间变异规律。且GWR模型的系数空间分布图可以反映环境变量在不同地理位置对SOM的空间非平稳性的影响程度,为探讨SOM在不同地形条件下的主导影响因子提供了依据,同时也为精确模拟过渡地带土壤有机质空间制图提供了重要的参考方法。     

闽北不同土地利用方式土壤蓄水量的研究

采用定位研究和土钻取样技术方法,观测2001~2003年间不同月份的土壤蓄水量数据,对闽北地区木荷林地、杉木林地、封山育林地和对照1m土层内的土壤蓄水量进行动态研究。研究结果表明:4种不同土地利用方式年、月平均土壤蓄水量大小顺序均为木荷林地>杉木林地>封山育林地>对照,且月平均土壤蓄水量变化趋势基本一致,呈明显的"W"模式,每年的1~6月份土壤蓄水量均较高,6月份以后土壤蓄水量处于下降时期,至9月或10月达到年内最小值,而后土壤水分支出处于下降阶段,土壤蓄水量又开始回升。木荷林地、杉木林地、封山育林地和对照不同层次月平均土壤蓄水量的变化明显不同,对照0~20cm土壤蓄水量变异比木荷林地、杉木林地和封山育林地明显。木荷林地、杉木林地和对照不同层次土壤蓄水量随深度的增加呈逐渐增大趋势,封山育林地在0~60cm深度内呈增加趋势,而在60~100cm深度内则有减小趋势。其不同层次土壤蓄水量的大小顺序均为木荷林地>杉木林地>封山育林地>对照。     

闽北不同土地利用方式径流量动态变化特征

采用定位研究方法和小集水区试验技术方法,通过两年的降雨量数据观测,对闽北地区木荷林地、杉木林地、封山育林地和对照等不同土地利用方式的小集水区进行坡面径流动态规律研究。研究结果表明:试验小区地表径流的产生主要是受降雨量的影响,而与降雨强度的关系不大,地表径流量与降雨量之间呈现出极显著的非线性二次抛物线关系(P<0.01)。4种不同土地利用方式的月平均径流量一般随月降雨量的增大而增大,并且在同1月份间其平均地表径流量的大小趋势为:对照>封山育林>杉木>木荷,均是在6月份达到最大值,9月份出现最小值。对照比木荷林地、杉木林地、封山育林地更容易产生地表径流,林地具有较好的涵养水源和保持水土作用。     

豫西黄土丘陵区不同土地利用方式土壤团聚体有机碳含量及其矿化特征

以豫西黄土丘陵区阔杂林、刺槐林、灌草地、果园和耕地土壤为对象,应用室内培养法,研究不同土地利用方式对土壤团聚体中有机碳含量及其矿化的影响,结果表明:不同利用方式地之间5mm,2~5mm两个粒级风干团聚体含量无显著差异,阔杂林、刺槐林、灌草地和果园5mm水稳性团聚体含量较耕地均显著提高,刺槐林和灌草地2~5mm水稳性团聚体含量较耕地显著提高;阔杂林、刺槐林、灌草地和果园土壤结构破坏率较耕地均显著降低,不同土地利用方式对团聚体的影响,主要表现在对较大粒级团聚体形成和稳定性的影响上。不同利用方式地均以0.25~2mm团聚体有机碳含量最高;同一利用方式地各粒级团聚体有机碳含量差异较小,但各粒级团聚体对有机碳贡献率差异较大,团聚体对有机碳的贡献率主要取决于团聚体的含量。不同利用方式地5,2~5,0.25~2mm 3个粒级团聚体中,有机碳的累积矿化量和矿化速率均为刺槐林地阔杂林地灌草地果园耕地;各粒级团聚体有机碳矿化速率变化规律基本一致,拟合符合对数函数;团聚体可矿化有机碳的分配比例随粒级减小而变大,大团聚的固碳能力较小团聚体强。     

土默川平原盐渍化土地不同利用方式的土壤质量评价

为评价盐渍化土地经不同利用方式后对土壤质量的影响,以土默川平原盐渍化土壤为研究对象,针对区域内的5种土地利用方式(盐荒地、改良地、牧草地、农田地、林地),采用主成分分析法从32项土壤物理、化学、生物学指标中选取关键指标,计算土壤质量综合指数以评价土壤质量,为该地区建立可持续的土地利用模式和区域生态恢复提供理论依据。结果表明:不同土地利用方式下的土壤物理、化学、生物性状存在一定差异。总体来看,林地、牧草地、农田地和改良地均能有效降低土壤盐渍化程度,改善土壤物理性状,增加土壤养分和微生物数量;表征土默川平原土壤质量的关键指标包括2～5 mm团聚体的有机碳、全盐量、饱和含水量、细菌、铵态氮和氯离子,其权重分别为0.35、0.23、0.17、0.10、0.08和0.06;4个土壤质量指数的结果表明,农田地、林地和牧草地的土壤质量指数均高于盐荒地、改良地。     

黄土丘陵沟壑区不同土地利用方式的土壤水分效应

采用定位监测法,对黄土丘陵沟壑区的延安燕沟不同土地利用方式下土壤水分动态变化规律进行了系统分析。结果表明,在2002年降雨前期较多后期较少的情况下,土壤水分4—10月间呈现总体下降趋势,降雨对土壤水分的补偿效应明显不足;不同植被下土壤水分季节变化存在明显差异,苹果园和退耕坡地土壤水分衰减幅度小,林灌草地则水分逐渐减小,变化幅度较大;植被对土壤水分的差异性利用使得土壤平均水分含量以及水分剖面分层均存在差异。各层土壤水分变异系数的垂直变化也因植被类型的不同而存在差异。除浅层0—10 cm外,不同层次土壤水分变化趋势较缓和,较一致。土壤含水量逐月下降,个别月份水分略有升高,说明降雨对土壤水分的补偿作用在该降雨年型下表现微弱。     

伊犁河谷不同土地利用方式下土壤粒度特征

为更有效地指导伊犁河谷水土环境的可持续发展,对河谷地区不同土地利用方式下的土壤进行采样,共获得14个剖面98个土壤样品。利用EASY SIZER20测定样品粒度,依据福克—沃德公式计算中值、平均粒径、标准偏差、峰度、偏度,采用Excel,SPSS 19.0等统计软件进行作图和统计分析。结果表明:(1)不同土地利用方式下土壤粒级百分含量虽有不同,但都是以粉粒(2~50μm)、砂粒(50~2 000μm)为主。其中耕地的粉粒、砂粒百分含量均高于荒地,林地、草地的黏粒(2μm)百分含量相当。(2)不同土地利用方式下土壤粒级的变异系数表现出显著性差异。耕地中粉粒、砂粒含量的变异系数普遍大于荒地,黏粒含量的变异系数则相反。(3)不同土地利用方式下土壤粒度特征不同,耕地的平均粒径明显大于草地、荒地、林地,荒地的分选性明显优于耕地、园地。     

不同土地利用方式下渭-库绿洲土壤盐渍化特征分析

基于渭干河—库车河三角洲绿洲土壤盐渍化现象发展的趋势,采用经典统计分析方法,对研究区不同土地利用方式下的土壤电导率、总盐量和pH值进行描述性统计分析,通过单因素方差方法对不同土地利用方式下土壤盐分指标进行差异显著性检验,并利用最小显著极差法(LSD)进行多重比较。研究结果表明:在不同土地利用方式和土层深度下,土壤电导率和总盐量的平均水平差异显著(p0.05),其含量由高到低依次为:荒漠灌丛盐碱草地耕地林地,而土壤pH值则无显著差异,土壤盐分呈现出明显的表层富集现象。本研究的结论对于提高此区域农业生产潜力和盐碱地综合治理具有重要的理论和实际意义。     

不同利用方式土地的土壤盐碱化特征差异

【目的】以3种利用方式(城市绿地、平原造林地、苗圃地)土地的土壤为研究对象,揭示土地利用方式对土壤盐碱化特征的影响,以期为合理选择造林和营林类型并有效地从成因上控制土壤盐碱化趋势以及土地利用的可持续发展提供科学依据。【方法】2022年春季在北京市通州区选取树种常见的城市绿地、平原造林地、苗圃地54个,分别采集0～20 cm、20～40 cm土层土壤样品324个,对各土层土壤全盐含量、主要阴阳离子含量及组成、碱化指标进行测定,采用单因素方差分析、相关性分析、克里金插值法对3种利用方式土地的土壤盐碱特征进行分析,并探讨其形成原因。【结果】研究区土壤总体呈碱性,土壤pH在8.39～8.53之间,盐化和碱化程度均为中度及以下。不同利用方式土地的土壤全盐含量、离子组成及分布存在差异,城市绿地土壤盐分呈“表聚”型分布,全盐量及Cl^-、Na⁺、Mg²⁺含量显著高于平原造林地和苗圃地,研究区土壤Na⁺变异系数最大,Ca²⁺变异系数最小。除Na⁺外,其它离子在城市绿地土壤中...     

不同土地利用方式土壤生态效应设计研究

参阅了大量的国内外学术论文,从多个方面、不同角度论述了不同土地利用方式土壤生态效益研究的必要性:从土壤生态恢复的目的、意义及概念出发,介绍了植被恢复与土壤生态的关系,土地利用方式与土壤环境以及与土壤生物酶活性的关系。据此提出了研究内容和技术路线,并预测出可能得出的研究成果。     

Physical properties of peat soils under different land use options

Pristine peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosity, von Post degree of decomposition) in soil profiles of two peatland forests, a cultivated peatland, a peat extraction area and two pristine mires originally within the same peatland area. Soil hydraulic conductivity of the drained sites (median hydraulic conductivities: 3.3 × 10^?5 m/s, 2.9 × 10^?8 m/s and 8.5 × 10^?8 m/s for the forests, the cultivated site and the peat extraction area, respectively) was predicted better by land use option than by soil physical parameters. Detailed physical measurements were accompanied by monitoring of the water levels between drains. The model ‘DRAINMOD’ was used to assess the hydrology and the rapid fluctuations seen in groundwater depths. Hydraulic conductivity values needed to match the simulation of observed depth to groundwater data were an order of magnitude greater than those determined in field measurements, suggesting that macropore flow was an important pathway at the study sites. The rapid response of depth to groundwater during rainfall events indicated a small effective porosity and this was supported by the small measured values of drainable porosity. This study highlighted the potential role of land use and macropore flow in controlling water table fluctuation and related processes in peat soils.     

Carbon budget in arable gray forest soils under different land use conditions

The effect of different land-use practices on the carbon budget in old arable gray forest soils of Russia was studied in field experiments. A short-term (for 6–7 years) cessation of mineral fertilization had no negative effects on the carbon budget in the agrocenoses studied. Only the combination of zero fertilization with the return to monoculture and the introduction of black fallows created a negative budget of humus in the soil. The regrassing of the eroded arable soil for 24 years increased the humus reserve in the 0- to 60-cm layer by a factor of 1.6–1.7. The average annual accumulation of carbon and nitrogen after the restoration of the perennial vegetation was 106–128 g C/m² and 11–16 g N/m², respectively.     

不同栽培方式菜田耕层土壤重金属状况

【目的】评价不同栽培方式(温室、大棚和露地)菜田土壤重金属状况,为菜田土壤质量改善和蔬菜高效安全施肥提供一定的理论依据。【方法】针对我国北方3个区域(东北、黄淮海、西北地区)和南方4个区域(华中、西南、华东、华南地区)主要蔬菜种植区不同栽培方式的典型菜田耕层土壤展开调查,选择的主要菜区不同栽培方式的菜田均为远离城郊的未受到工业“三废”、汽车尾气等污染的农村菜田,取样时间是2013年作物收获后或蔬菜施肥前或生长后期,共采集503个土壤样品,对温室、大棚和露地三种栽培方式下土壤重金属状况进行了研究。【结果】1)采样区设施(温室和大棚)菜田土壤重金属Cu、Zn和Cd总量总体上均高于露地菜田土壤,较露地菜田土壤平均分别高12.2%、21.7%和30.4%。2)随着种菜年限的增加,菜田土壤重金属Cu、Zn和Cd总量呈显著增加的趋势。不同栽培方式菜田土壤中均可能存在几种重金属同时污染的复合污染现象,土壤Cu、Zn、Cd等之间的相关性均达到极显著水平。3)采样区不同栽培方式菜田土壤Cd的二级超标率在19.2%~22.3%之间,温室、大棚和露地菜田土壤Cd的单项污染指数平均分别为0.97、0.98和0.70;土壤Cu、Zn、Pb、Cr、As和Hg的二级超标率在0~14.6%之间,单项污染指数在0.06~0.52之间。【结论】设施菜田N、P2O5和K2O总量及有机肥用量均显著高于露地菜田,可能是造成设施菜田土壤中重金属Cu、Zn和Cd积累显著高于露地菜田的重要原因。采样区设施(温室和大棚)菜田土壤Cd总体上处于污染警戒级状态,露地菜田土壤总体上未受到Cd的污染;设施和露地菜田土壤Cu、Zn、Pb、Cr、As和Hg总体上均未构成对土壤的污染。     

Kinetics of phosphorus release from calcareous soils under different land use in Iran

The rate of phosporus (P) release from soils can significantly influence P fertility of soils. The objectives of this study were to investigate the effects of land‐use types on the kinetics of P release under different management practices and the relationship between kinetic parameters and soil physical and chemical properties from calcareous soils. The kinetics of P release in 0.01 M CaCl₂ was studied in surface samples of 30 calcareous soils planted to garlic, garden, pasture, potato, vegetables, and wheat. Trend in P‐release kinetics was similar between land‐use types. Significantly different quantities of P were released under different land use. The maximum amount (average of five soils) (46.4 mg kg^–1) of P was released in soil under potato and the minimum amount (10.4 mg kg^–1) under pasture. The kinetics of P release from soils can be described as an initial rapid rate followed by a slower rate. Different models were used to describe P release. In general, parabolic diffusion and power equation were found to be appropriate for modeling P release. The P‐release rate for the soils was estimated by parabolic equation for the studied land‐use types. The constant b was lower for pasture and wheat than for garlic and potato. The relationship between the rate of P release with Olsen‐P was linear, while it was curved with respect to the CaCl₂‐P, indicating that release of P was diffusion‐controlled. When the kinetic parameters of models were regressed on soil properties, CaCl₂‐P and CaCO₃ appeared to be the most important soil properties influencing P‐release rates in these soils.     

Enzymatic activity inside and outside of water-stable aggregates in soils under different land use

A method is presented for assessing the distribution of enzymatic activity inside and outside of water-stable aggregates. Two samples of water-stable aggregates >1 mm have been isolated from dry aggregates of 1–2 mm. To determine the enzymatic activity, a substrate has been added to one of the samples without disaggregation; the other sample has been preliminarily disaggregated. Enzymatic activity within waterstable aggregates has been assessed from the difference between the obtained results under the supposition that the penetration of substrate within the water-saturated aggregates is hampered, and enzymatic reactions occur only at the periphery. The levels and distributions of enzymatic (peroxidase, polyphenol oxidase, and catalase) activities in water-stable aggregates of soddy-podzolic soils under forest and plowland and typical chernozems of long-term field experiments have been studied. The peroxidase, polyphenol oxidase, and catalase activities of water-stable aggregates vary from 6 to 23, from 7 to 30, and from 5 to 7 mmol/(g h), respectively. The ratio between the enzymatic activities inside and outside of soil aggregates showed a higher dependence on soil type and land use, as well as on the input of organic matter and the structural state, than the general activity level in water-stable aggregates.     

Fertility of tropical soils under different land use systems—a case study of soils in Tabasco,Mexico

Increasing deforestation in Mexico in the past 40 years has led to significant land use changes. It is important to establish land use systems that allow for the necessities of an increasing population and the conservation of soil fertility in the long term. In this study, we investigated the influence of different land use forms on soil fertility in Tabasco, SE Mexico. We chose two different commonly used pastures (Cynodon plectostachyus and Brachiaria decumbens) and a succession forest. We characterised soil fertility by physico-chemical parameters (texture, density, pH, P, Corg., Ntot., cation exchange capacity (CEC)) as well as by biological parameters, such as litter decomposition, microbial biomass and earthworm community. To estimate litter decomposition we used leaves of Gliricidia sepium, a common fodder tree in the region. The three land use systems had very similar soil chemical characteristics. All three can be characterised as acidic (pH between 4.1 and 5.3) with a high content of organic matter and total nitrogen. However, the three land use systems differed significantly with respect to their soil biological characteristics. Earthworm density as well as litter decomposition were significantly lower under B. decumbens than in the other soils. In all land use systems, the participation of macrofauna and mesofauna accelerated litter decomposition rate significantly as compared with decomposition with microfauna and microflora alone.We extracted two components of the pool of data by main component analysis. The acidity component explained mainly the microbial litter decomposition rate. The rate of litter decomposition – with participation of soil meso- and macrofauna – could be explained by the humus component. We assume that biological parameters were more suitable to characterise differences between the different land use systems. The use of C. plectostachyus and succession forest showed a positive effect on soil fertility.     

不同土地利用方式土壤对铜、镉离子的吸附解吸特征

采用一次平衡法对Cu²⁺、Cd²⁺在城市及城郊农田、林地、草地3种土地利用方式土壤中的吸附解吸过程进行比较研究, 结果表明: Cu²⁺、Cd²⁺在3种土地利用方式土壤中的吸附量均随平衡液浓度的增加而增大, Cu²⁺、Cd²⁺在农田土壤上的吸附量均高于林地和草地土壤。分别用Langmuir和Freunlich两种等温吸附方程对吸附过程进行拟合, 3种土壤对Cu²⁺的吸附过程运用Langmuir方程拟合效果好, 而对Cd²⁺的吸附过程运用Freunlich方程拟合效果更好。Cu²⁺在3种土壤的解吸量大小顺序为农田>林地>草地, Cd²⁺在3种土壤的解吸量大小顺序为农田>草地>林地。两种离子在3种土壤中的动态吸附是个快速反应的过程, 随时间延长, 吸附反应趋于平衡。运用双常数函数方程和Elovich方程能较好地拟合重金属在土壤上的吸附动力学过程。Cu²⁺、Cd²⁺的吸附与土壤黏粒含量、有机质含量、CEC和pH均有关。     

Chemical fractionation of phosphorus in calcareous soils of Hamedan,western Iran under different land use

We investigated the effects of land uses on P distribution and availability in selected calcareous soils under different management practices. KCl‐P (labile P), NaOH‐P (Fe‐Al‐bound P), HCl‐P (Ca‐bound P), and residual P (Res‐P) fractions at 0–30 cm depth were determined for soils planted to garlic, orchard, pasture, potato, leafy vegetables, and wheat. Trends in P distribution between chemical fractions were similar between land uses. Ca‐bound P was the most abundant P fraction in the soils, constituting between 61% and 78% of the total P, whereas P associated with labile was less abundant (< 2%). Soils under leafy vegetables and wheat along with pasture presented the highest and lowest values in all fractions of P, respectively. Labile P generally was highest for leafy vegetables and potato. Labile P and Fe‐Al‐bound P comprised < 1.4% and 8% of total P, respectively. Residual P ranged from ≈ 14% (potato and garlic) to 31% (pasture). Long‐term fertilization increased P allocation to inorganic fractions, as Ca‐bound P contained 78% of total P for potato and garlic and 74% for leafy vegetables but 61% for pasture. A strong positive correlation between labile P and Fe‐Al‐bound P (r = 0.534, p < 0.01), labile P and Ca‐bound P (r = 0.574, p < 0.01), Ca‐bound P and Fe‐Al‐bound P (r = 0.504, p < 0.01), Olsen‐P and CaCl₂‐P (r = 0.821, p < 0.01) was found. Principal‐component analysis showed that the first four components accounted for most of the variation, 32.5%, 16.9%, 12.9%, and 7.9% of total variation, respectively.     

不同土地利用方式下紫色土中铵的容量和强度（Q/I）关系

研究了4种土地利用方式下(水田、旱地、林地、菜地)紫色土(紫色湿润雏形土)和紫色水稻土(紫色水耕人为土)NH4+的容量和强度(Q/I)关系。结果表明:紫色土和紫色水稻土NH4+Q/I曲线的曲线部分均出现在NH4+的活度比(ARNH4)较低时,表明土壤存在非交换性NH4+(或专性吸附的NH4+)的释放。紫色土和紫色水稻土NH4+的潜在缓冲容量(PBC)为71.47～203.7 cmol kg-1(mol L-1)-1/2;土壤活性NH4+(-ΔNH40)为0.029 5～0.089 7 cmol kg-1,NH4+的平衡活度比(AR0NH4)为0.187×10-3～1.255×10-3(mol L-1)1/2;土壤专性吸附位点(NH4-sas)为0.010 6～0.118 5 cmol kg-1。相关分析和通径分析表明,土壤小于0.002 mm黏粒含量与NH4+PBC及NH4-sas均呈极显著正相关(p<0.01),小于0.002 mm黏粒对PBC的影响主要是间接作用(间接通径系数为0.585),但对NH4-sas则有强烈的直接作用;有机碳与-ΔNH40和AR0NH4均呈极显著正相关(p<0.01),但是有机碳对-ΔNH40有较大的直接效应(直接通径系数为0.966),而对AR0NH4的影响主要以间接效应为主。土壤-ΔNH40与交换性NH4+数值接近且呈极显著相关(r=0.876 4,n=8,p<0.01),而AR0NH4与交换性NH 4+亦呈极显著相关(r=0.983 7,n=8,p<0.01)。土壤小于0.002 mm黏粒和有机碳的差异是导致不同土地利用方式下紫色土交换性NH4+以及Q/I参数的差异的主要原因,交换性NH4+标志的NH4+有效性指标与由Q/I关系得到的NH4+有效性指标类似。     

Similar quality and quantity of dissolved organic carbon under different land use systems in two Canadian and Chinese soils

Purpose

The quality and quantity of dissolved organic carbon (DOC) in the soil can be used as indicators of the effects of perturbations on soil C. We studied the effects of land use systems (native forest, grassland, and arable land) in both Alberta, in western Canada, and Heilongjiang, in northeast China, on the quality and quantity of soil DOC.

Materials and methods

We studied the UV absorption, humification index (HIX), and biodegradability of water-extractable organic C, which is operationally defined as DOC. The relationship between biodegradability and the structural chemistry of soil organic matter studied with ¹³C-nuclear magnetic resonance (NMR) spectroscopy was also investigated.

Results and discussion

The UV absorption and HIX, biodegradability of DOC, and the proportion of organic matter functional groups were not different among the land use types in both Canada and China. When the samples from both countries were considered together, the extractability of DOC was negatively correlated with soil organic carbon content and carbonyl C, and positively correlated with O-alkyl C; the biodegradability of DOC was positively correlated with soil C/N ratio, and negatively correlated with the specific UV absorbance and HIX.

Conclusions

The main effect of land use type on soil organic matter was on its content but not the labile C characteristics or organic matter functional group composition, indicating the dominant control of the climate on the quality of DOC of the organic matter under different land use types we studied in the two cold temperate regions.